Diagnostic Value of Vitamin D Status and Bone Turnover Markers in Rheumatoid Arthritis Complicated by Osteoporosis.

OBJECTIVE: To research the diagnostic performance of clinical potential bone turnover indexes in rheumatoid arthritis (RA) complicated with osteoporosis (OP).

METHODS: This study involved 87 RA patients, 48 with OP, and 39 without OP, and 204 non-RA control patients, including those with systemic lupus erythematosus, ankylosing spondylitis, primary Sjogren's syndrome, systemic sclerosis, and healthy patients. The levels of 25-hydroxyvitamin D [25(OH)D], β-crosslaps (β-CROSSL), parathyroid hormone (PTH) were measured by electrochemiluminescence (ECLIA), and the level of bone alkaline phosphatase (BALP) was measured by lectin affinity method.

RESULTS: The serum concentration of 25(OH)D in the RA with OP group was significantly lower than the control group ( P <0.01), while the levels of β-CROSSL, BALP in the RA with OP group considerably exceeded those found in the control group ( P <0.01). The levels of β-CROSSL and PTH were significantly higher in RA patients with OP than without OP ( P <0.01), while the level of 25(OH)D was statistically lower than without OP ( P <0.01). An unconditional logistical regression analysis proved an association with low 25(OH)D and elevated β-CROSSL in RA with OP, with 25(OH)D demonstrating greatest diagnostic potential according to the ROC curve.

CONCLUSION: The significantly reduced levels of 25(OH)D and excessive β-CROSSL may indicate a high risk of the secondary osteoporosis in RA patients.